The present invention relates to a process for preparing by chemical vapour deposition or CVD of a multilayer coating based on Ti--Al--N, i.e. a multilayer coating of TiN and Ti.sub.1-x Al.sub.x N, in which e.g. the Ti.sub.1-x Al.sub.x N layers can have variable compositions. The invention also relates to the coating prepared by this process.
More specifically, the present invention relates to a process for the preparation of a multilayer coating, comprising a stack, on a substrate, of several layers chosen from among layers constituted by TiN and layers constituted by (Ti,Al)N, also known as Ti.sub.1-x Al.sub.x N, the complete coating being produced in a single, continuous operation by thermal chemical vapour deposition (CVD) from a gaseous mixture comprising a reducing gas, such as ammonia or nitrogen, hydrogen and titanium and optionally aluminium chlorides, the nature and/or composition of each layer being instantaneously adjusted by modifying the reducing gas to hydrogen molar ratio in the gaseous mixture.
The technical field of the invention can be generally defined as that of the deposition of thin layers or films on substrates with a view to improving their properties.